Catalysis Science & Technology
·
2021
·Vol. 12
·期 3
·762-772
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IF 6.119
Yitao Liu,Xianglin Liu,Zixu Yang,Hu Li,Xiaoxu Ding,Minjie Xu,Xinli Li,Wei-Feng Tu,Minghui Zhu,Yi-Fan Han
We reported a χ-Fe5C2/MgO catalyst for olefin synthesis directly from syngas (STO), showing high selectivity to C2–C4 olefins and catalytic stability. With characterization of the morphology, electronic structures, and adsorption/desorption properties using in/ex situ techniques (XPS, TEM, XRD, MES, PHTA and TPD), we revealed that MgO could act not only as a structural promoter to disperse the active iron phase and prevent particle agglomeration during the reaction, but also as an electronic modifier to transfer electrons to iron. In particular, by combination of spectroscopy and theory calculations, we have proved that the close intimacy between χ-Fe5C2 and MgO (∼0.3 electrons transfer from MgO to χ-Fe5C2) enhanced CO dissociative adsorption whilst weakening the secondary hydrogenation of olefins, leading to the enhancement of selectivity. The dual roles of MgO in χ-Fe5C2/MgO may shed light upon rational design of practical STO catalysts by taking advantage of the exceptional strong metal–support interactions (SMSIs).
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WATER RESEARCH
·
2021
·
IF 11.236
Lifa Ge,Yamei Yue,Wei Wang,Fatang Tan,Shenghua Zhang,Xinyun Wang,Xueliang Qiao,Po Keung Wong
Currently existing Fenton-like catalysts were limited in wastewater treatment owing to their potential transition-metal poisoning, narrow applicable pH range and high dependence on external energy excitation. In this work, the MgNCN/MgO nanocomposites were firstly synthesized by a facile one-pot calcination of melamine and basic magnesium carbonate, and used as novel H 2 O 2 activator for antibiotic removal. It was found that the MgNCN/MgO composite calcined at 550°C with the mass ratio of melamine to basic magnesium carbonate at 2:1, exhibited an excellent catalytic ability to tetracycline (TC) degradation in a wide pH range of 4-10 without any external energy input. More than 90% of TC (100 mL, 50 mg/L) could be degraded within 30 min by 10 mg of the nanocomposite in the presence of 0.2 mL of 30 wt% H 2 O 2 . Based on the experimental results, it was concluded that the Mg-N coordination between MgNCN and MgO in MgNCN/MgO nanocomposites activated H 2 O 2 to produce primary singlet oxygen ( 1 O 2 ) and minor hydroxyl radicals (·OH), responding for TC degradation. In addition, the degradation pathways of TC were deduced by determining the generated intermediates during the degradation process. This work provided a novel idea for designing transition-metal-free catalysts for nonradical activation of H 2 O 2 in the absence of external energy excitation.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2021
·Vol. 28
·期 29
·39513-39523
·
IF 4.223
He Jun,Song Wenchao,Huang Xiaohan,Gao Zuoyu
Magnesium oxide/expanded graphite (MgO/EG) catalyst was synthesized and applied for enhancing the degradation of Cu-ethylenediaminetetraacetic acid (Cu-EDTA) in an aqueous solution. The MgO/EG catalyst was characterized by XRD, SEM, EDS, and FTIR. For assessing the catalytic activity of MgO/EG, essential influencing factors were investigated including catalyst dosage, O 3 dosage, initial pH, initial Cu-EDTA concentration, and coexisting ions. The results show that the catalytic material showed high catalytic oxidation capacity for the Cu-EDTA removal in the MgO/EG/O 3 system. 100% of Cu(II) and 73.2% of TOC removal efficiency could be achieved in the MgO/EG/O 3 system at the reaction times of 90 min. This efficiency was higher than that seen for other systems, including O 3 alone (Cu(II) 81.4%/TOC 60.6%), EG/O 3 (84.2%/64.1), MgO/EG (< 4%/< 4%), and EG (< 4%/< 4%). A small decrease in the Cu(II) and TOC removal rate was observed after three runs in the stability and reusability experiments of the catalyst. Assays with radical scavenging experiments confirmed that MgO/EG-mediated oxidation was dependent on a hydroxyl radical pathway. The UV–vis spectra confirmed that the absorption peak of Cu-EDTA was gradually decreased and finally disappeared.
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CONSTRUCTION AND BUILDING MATERIALS
·
2020
·
IF 4.419
Yang Chen,Chengji Deng,Xing Wang,Jun Ding,Chao Yu,Hongxi Zhu
Si 3 N 4 -MgO-C refractories were prepared using fused magnesia, flake graphite, and Si powder-supported Fe(NO 3 ) 3 ·9H 2 O as the raw materials and phenolic resin as the binder under the flow of N 2 . The effect of different nitriding temperatures on the morphology and production of Si 3 N 4 in the uncatalyzed refractories was investigated. The effect of the morphology of β-Si 3 N 4 on the properties of the refractories with different catalyst contents was investigated. The oxidation resistance of the refractories was also investigated. The results showed that the increase in the nitriding temperature was beneficial for the formation of β-Si 3 N 4 in the refractories. However, very high nitriding temperatures generated a large number of pores in the refractories and deteriorated their properties. The refractory with 1 wt% catalyst exhibited good mechanical properties and oxidation resistance. However, the addition of excessive catalyst inhibited the formation of β-Si 3 N 4 and deteriorated the performance of the refractories.
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CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Jiefu Lang,Ke Ren,Yiguang Wang
As a thermal barrier coating (TBC) material, 8 wt% yttria-stabilized zirconia (8YSZ) exhibits poor resistance against calcium–magnesium–aluminosilicate (CMAS) corrosion. This is caused by the penetration of molten CMAS glass and the depletion of Y 3+ , which limits the lifetime of 8YSZ. In this study, a multi-rare-earth-oxide-doped zirconia (15 wt% (Lu 0.2 Yb 0.2 Dy 0.2 Gd 0.2 Y 0.2 )–ZrO 2 , denoted as 15LYDGY–SZ) ceramic was prepared to examine its interaction with CMAS. The sluggish diffusion effect and the competition between various dopant elements toward reaction with CMAS effectively slow down the atomic diffusion and limit the transformation of tetragonal phase into monoclinic phase in 15LYDGY–SZ ceramic. Compared with the currently used 8YSZ ceramic, the corrosion resistance of 15LYDGY–SZ to CMAS and its retention rate of fracture toughness after CMAS corrosion are improved. The results show that the multi-rare-earth-oxide-doped zirconia ceramic prepared in this study is a promising candidate material for the development of future TBCs.
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Catalysis Science & Technology
·
2016
·Vol. 7
·期 1
·168-180
·
IF 5.287
Xiaoxiong Huang,Yong Men,Jinguo Wang,Wei An,Yuanqiang Wang
A series of magnesia–silica binary composite catalysts with different molar ratios were prepared using various preparation methods and evaluated for the one-step production of 1,3-butadiene (BD) from bio-ethanol. The MgO–SiO2 catalyst prepared by wet-kneading is distinguished from the samples prepared by other methods by its superior activity. An exceptionally high productivity of butadiene with the high ethanol conversion of 95% and BD selectivity of 77% was obtained over wet-kneaded hierarchical flower-like MgO nanostructures with the catalytic material made up of SiO2 spheres (with a MgO : SiO2 molar ratio of 65 : 35 at 450 °C and an WHSV of 4.1 h−1), which translates into an unprecedented BD yield of 0.025 mol gcat−1 h−1. The as-prepared catalysts were characterized by XRD, FESEM, BET, FT-IR, UV/vis, CO2-TPD and NH3-TPD. The Mg precursor used and the preparation method are found to influence the extent of MgO and SiO2 interactions during preparation, as estimated by various techniques, which, in turn, was found to correlate with the catalytic performance. A subtle balance of surface acidity/basicity was found to be necessary to achieve a high butadiene yield which can be obtained by variation of MgO : SiO2 ratios in wet-kneaded samples. In view of the difference in catalytic activity and the physicochemical properties of the MgO–SiO2 composite catalysts, the Si–O–Mg chemical bond formed by the strong MgO and SiO2 interaction is suggested to be essential for the balanced surface acid/base sites in relation to the strong interaction between MgO and SiO2 and the consequent high catalytic performance.
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CATALYSIS TODAY
·
2016
·
IF 4.312
Kun Jiang,Dong Sheng,Zihao Zhang,Jie Fu,Zhaoyin Hou,Xiuyang Lu
Mixed MgO–Al 2 O 3 (with different Mg/Al ratio) supported nickel catalysts were prepared via co-precipitation method and used for hydrogenation of levulinic acid to γ-valerolactone under mild condition. Characterization results indicated that mixed MgO–Al 2 O 3 supported Ni catalysts possessed bigger surface area than that of Ni/MgO and Ni/Al 2 O 3 , and Ni dispersed highly on the surface of mixed MgO–Al 2 O 3 support. It was found that mixed MgO–Al 2 O 3 supported Ni catalysts were more active and selective for the hydrogenation of levulinic acid to γ-valerolactone than that of Ni/MgO and Ni/Al 2 O 3 , and the best yield of γ-valerolactone at 160 °C, 1 h and 3 MPa H 2 reached 99.7% over Ni/MgAlO 2.5 , and Ni/Mg 2 Al 2 O 5 could be recycled without obvious loss of its initial activity.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2017
·
IF 2.843
Lei Wang,Zhiming Zhou,Yuanwu Hu,Zhenmin Cheng,Xiangchen Fang
A series of nanosheet MgO-based sorbents promoted by mixed-alkali-metal nitrate and carbonate were prepared by a simple precipitation–deposition method and applied to CO2 capture. The structural properties of these sorbents were characterized by various techniques, and their CO2 capture performance was evaluated using a thermogravimetric analyzer. Compared to the sorbent derived from commercial MgO, the nanosheet MgO-based sorbent had faster and higher CO2 uptake, because of its thin-sheet structure. Among various alkali-metal-salt-promoted nanosheet MgO, the sorbents promoted with mixed-alkali-metal nitrates (LiNO3 and KNO3) and carbonates (Na2CO3 and K2CO3) exhibited a high total CO2 uptake at a respectable rate. In particular, the sorbent with a MgO content of 73 wt % and a nitrate/carbonate molar ratio of 2 possessed the highest total CO2 uptake and the best cyclic stability, with a total uptake of 0.52 gCO2/gsorbent and MgO conversion of 65% after 20 cycles (60 min of absorption in 40% CO2/60% N2 at 350 °C, 15 min of regeneration in 100% N2 at 400 °C). Based on the structure–activity relationship of the sorbents, a possible mechanism consisting of three stages was presented for the CO2 absorption process, in which the dissolution of CO2 and carbonation in the molten nitrate played an important role.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Liqing Zhang,Bo Li,Yonggang Wei,Haoyuan Xu
Environmental problems caused by Cr(VI) need to be solved urgently. As a green and safe adsorbent, magnesium oxide has the characteristics of strong adsorption capacity and safety, non-toxic and harmless. In this study, high-performance Cr(VI) adsorption material (F-MgO) was prepared by combination hydrothermal modification of recycling MgO and doping of solid waste fly ash with the MgO that was a by-product of high magnesium laterite nickel ore. The adsorption properties of F MgO composites for Cr(VI) were evaluated, and the maximum adsorption capacity of Cr(VI) by F MgO reaches 172.6 mg/g at pH = 2.0. The F-MgO also showed high stability and excellent cycle adsorption performance. The adsorption mechanism was extensively studied by adsorption kinetics and DFT theoretical calculation, and electrostatic adsorption and chemical interaction between Cr(VI) and F MgO active sites were demonstrated. The prepared F MgO composites from waste resources with a simple synthetic method have great potential in the treatment of chrome-containing wastewater to achieve the purpose of treating waste with waste.
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JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
·
2024
·
IF 3.1
Chen Yang,Li Zeng-yi,Tan Hao-bo,Fu Yu-ran,Ding Jun,Deng Cheng-ji,Yu Chao
To solve the problem of poor high-temperature service performance caused by low carbonization of MgO–C refractories, low-carbon MgO–C refractories with excellent thermal shock, oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al 2 O 3 powders as additives. The results indicated that the addition of micro-Al 2 O 3 powders optimized the internal structure of the material, like the columnar β-Si 3 N 4 with a stepped distribution and the mosaic structure formed between granular and flaky Mg 2 SiO 4 , which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance. Specifically, the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa, respectively. Moreover, the addition of micro-Al 2 O 3 powders promoted the formation of fine particles of Mg 2 SiO 4 , MgAl 2 O 4 and MgO, as well as a dense protective layer of Mg 2 SiO 4 in the material under high-temperature environment. Furthermore, spinel and high-temperature solid solution were formed in the corrosion environment. The oxidation and corrosion resistances were greatly improved by 41% and 15%, respectively.
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JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Zijie Lu,Haokun Bai,Lanlan Liang,Shuo Chen,Hongtao Yu,Xie Quan
Heterogeneous catalytic ozonation (HCO) enables the destruction of organic pollutants in wastewater via oxidation by powerful hydroxyl radicals (·OH). However, the availability of short‐lived ·OH in aqueous bulk is low in practical treatment scenarios due to mass transfer limitations and quenching of water constituents. Herein, we overcome these challenges by loading MgO catalysts inside the pores of a tubular ceramic membrane (denoted as CCM) to confine ·OH within the nanopores and achieve efficient pollutant removal. When the pore size of the membrane was reduced from 1000 to 50 nm, the removal of ibuprofen (IBU) by CCM was increased from 49.6 % to 90.2 % due to the enhancement of ·OH enrichment in the nanospace. In addition, the CCM exhibited high catalytic activity in the presence of co-existing ions and over a wide pH range, as well as good self-cleaning ability in treating secondary wastewater. The experimental results revealed that ·OH were the dominant reactive oxygen species (ROS) in pollutant degradation, while surface hydroxyl groups were active sites for the generation of ·OH via ozone decomposition. This work provides a promising strategy to enhance the utilization of ·OH in HCO for the efficient degradation of organic pollutants in wastewater under spatial confinement.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2024
·
IF 8
Wanqi Zhang,Zhicong Sun,Yuhang Tian,Yaoting Mou,Yemin Guo,Xia Sun,Falan Li
Streptomycin (STR) is an antibiotic fungicide that is easily enriched in the environment and threatens human health. In this paper, a ratiometric fluorescence aptasensor with silver nanoclusters-skimmed milk powder@zeolitic imidazolate framework-8 (AgNCs-SMP@ZIF-8) fluorescent material as the response signal and carbon quantum dots (CQDs) functionalized with aptamer as the reference signal was prepared. Magnetic graphene oxide selection technology was used to screen high-affinity STR-specific aptamer. The truncation strategy for removing non-binding site bases was based on molecular simulation docking, and it was found that the stem-loop structure formed by the truncated aptamer 52 (Apt52) was used for STR-specific recognition and had a higher STR affinity ( K d = 14.52 nM) compared to the initial 79-nucleotide aptamer. AgNCs was then covered in a protein coating and encapsulated in ZIF-8 to obtain AgNCs-SMP@ZIF-8 with enhanced red fluorescence intensity . The added Cu 2+ rapidly penetrated into ZIF-8 to induce red fluorescence quenching , while the CQDs modified by Apt52 maintained green fluorescence. Hence, the constructed ratiometric fluorescent sensor with Apt52 as the recognizing element can detect STR within 90 s with a detection limit of 0.98 nM. The ratiometric probe proposed has considerable potential for STR residue detection in milk.
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